Question

A dynamometer D is attached to two bodies of masses M=6kg. forces F=20N are appliedon the masses. What will be the reading of the dynamometer?

Answer 1

Let x be the force recorded by a dynamometer.

Both masses move in one direction.

The largest force is 20N and the least is 10 N.

This means x lies between 10 and 20.

This can be represented as shown.

$10<x<20$

The resultant force on :

$6kgmass=20-x$

$4kgmass=x-10$ They have equal acceleration as shown :

$(20-x)/6=(x-10)/4$

$4(20-x)=6(x-10)$

$80-4x=6x-60$

$140=10x$

$x=14N$

The acceleration is :

$(20-14)/6=1m/s²$